Field emission electron source and production method thereof

Abstract

In a field emission-type electron source ( 10 ), a strong field drift layer ( 6 ) and a surface electrode ( 7 ) consisting of a gold thin film are provided on an n-type silicon substrate ( 1 ). An ohmic electrode ( 2 ) is provided on the back surface of the n-type silicon substrate ( 1 ). A direct current voltage is applied so that the surface electrode ( 7 ) becomes positive in potential relevant to the ohmic electrode ( 2 ). In this manner, electrons injected from the ohmic electrode ( 2 ) into the strong field drift layer ( 6 ) via the n-type silicon substrate ( 6 ) drift in the strong field drift layer ( 6 ), and is emitted to the outside via the surface electrode ( 7 ). The strong field drift layer ( 6 ) has: a number of semiconductor nanocrystals ( 63 ) of nano-meter order formed partly of a semiconductor layer configuring the strong field drift layer ( 6 ); and a number of insulating films ( 64 ) each of which is formed on the surface of each of the semiconductor nanocrystals ( 63 ) and each having film thickness to an extent such that an electron tunneling phenomenon occurs.

1. A field emission-type electron source comprising:
 an electrically conductive substrate;  
 a strong field drift layer formed on said electrically conductive substrate; and  
 a surface electrode formed on said strong field drift layer, in which  
 said strong field drift layer has a number of semiconductor nanocrystals of nano-meter order formed partly in a semiconductor layer configuring said strong field drift layer, and a number of insulating films, each of which is formed on a surface of each of said semiconductor nanocrystals and has a thickness smaller than a crystalline particle size of each of said semiconductor nanocrystals, wherein  
 a voltage can be applied between said surface electrode and said electrically conductive substrate so that said surface electrode becomes higher in potential, whereby electrons injected from said electrically conductive substrate into said strong field drift layer drift in said strong field drift layer, and are emitted through said surface electrode, and  
 each of said insulating films formed on each of the surface of each of said semiconductor nanocrystals has such a thickness that an electron tunneling phenomenon occurs.  
 
     
     
       2. The field emission-type electron source according to  claim 1 , wherein water content of said insulating film formed on the surface of each of said semiconductor nanocrystals is substantially zero. 
     
     
       3. The field emission-type electron source according to  claim 1 , wherein a compound layer or an alloy layer composed of a semiconductor and a metal is interposed at an interface between said semiconductor layer configuring said strong field drift layer and said electrically conductive substrate. 
     
     
       4. The field emission-type electron source according to  claim 1 , wherein said semiconductor layer is almost crystallized at the interface between said semiconductor layer configunng said strong field drift layer and said electrically conductive substrate. 
     
     
       5. A method of manufacturing a field emission-type electron source having:
 an electrically conductive substrate;  
 a strong field drift layer formed on said electrically conductive substrate; and  
 a surface electrode formed on said strong field drift layer, in which  
 said strong field drift layer has a number of semiconductor nanocrystals of nano-meter order formed partly in a semiconductor layer configuring said strong field drift layer, and a number of insulating films, each of which is formed on a surface of each of said semiconductor nanocrystals and has such a thickness that an electron tunneling phenomenon occurs, wherein  
 a voltage can be applied between said surface electrode and said electrically conductive substrate so that said surface electrode becomes higher in potential, whereby electrons injected from said electrically conductive substrate into said strong field drift layer drift in said strong field drift layer and is emitted through said surface electrode, said method being characterized in that  
 each of said insulating films is formed on the surface of each of said semiconductor nanocrystals by any one of an electrochemical process, a rapid thermal oxidization process, a rapid thermal nitriding process, and a rapid thermal oxidization and nitriding process, or alternatively, a combination of those processes.  
 
     
     
       6. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein annealing processing at a temperature of 700° C. or less is carried out in a vacuum, in an inert gas, in a foaming gas, or in a nitride gas after said insulating films have been formed on the surfaces of said semiconductor nanocrystals. 
     
     
       7. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein a heat treatment by a rapid heating process at a temperature of 600° C. or more is carried out in an atmosphere containing an oxide species or a nitride species after said insulating firms have been formed on the surfaces of said semiconductor nanocrystals. 
     
     
       8. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein annealing processing by a rapid heating process at a temperature of 600° C. or more is carried out in an inert gas atmosphere after said insulating films have been formed on the surfaces of said semiconductor nnanocrystal. 
     
     
       9. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein annealing processing is carried out in a vacuum or in an inert gas after said semiconductor nanocrystals have been formed. 
     
     
       10. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein annealing processing is carried out in a vacuum or in an inert gas after said semiconductor layer has been formed on said electrically conductive substrate. 
     
     
       11. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein after said insulating films have been formed on the surfaces of said semiconductor nanocrystals, there are carried out one or more than once at least two processes of:
 a first processing comprising carrying out at least one of annealing processing at a temperature of 700° C. or less and annealing processing by gas species capable of defect compensation in a vacuum, in an inert gas or in a foaming gas;  
 a second processing comprising carrying out a heat treatment by a rapid heating process at a temperature of 600° C. or more in an atmosphere containing an oxide species or a nitride species; and  
 a third processing comprising carrying out annealing processing by a rapid heating process at a temperature of 600° C. or more in an inert gas atmosphere.  
 
     
     
       12. The method of manufacturing the field emission-type electron source according to  claim 5 , wherein annealing processing in hydrogen, hydrogen radical emission processing, or hydrogen radical emission annealing processing is carried out during at least one of a period after forming said semiconductor layer, a period after forming said semiconductor nanocrystals, and a period after forming said insulating films on the surfaces of said semiconductor nanocrystals. 
     
     
       13. The field emission-type electron source according to  claim 1 , wherein the thickness of each of said insulating films is in the range of 1 nm to 3 nm.